Field of the Invention
The present invention relates to food sorting and, more particularly, to the sorting of food by consecutive automatic inspection of a plurality of characteristics of the particular food.
Specifically, the present invention relates to an automatic food sorting and inspection system comprising a novel sequence of grading and removal stations, each of which senses a particular characteristic of the food passing therethrough. The sorting and inspection system of the present invention has particular usefulness for grading husked of ears of corn.
Photoelectric devices and methods have been employed in the past for the sorting of food according to maturity and quality. Such food-sorting methods have generally employed a light source which illuminates the food with light and logic circuitry to measure the characteristics of the light reflected from the surface of the food to provide an indication of the maturity of the food. The most usual characteristic of the food which is measured as an indication of maturity is the color of the light which is reflected from the food. For example, in instances in which apples are to be graded according to maturity, the color of light which is reflected from the surface of the apple will vary from predominately green when the apple is immature to predominately red when the apple has fully matured. Thus, as the apples become fully mature, the intensity of the light in the red spectrum which is reflected from the apple will increase and will provide an indication of the maturity of the apple which may be measured automatically. An example of a produce grader which operates on a similar principle is U.S. Pat. No. 4,095,696, issued June 20, 1978, to Sherwood, which utilizes reflected light to separate vegetables, such as red tomatoes, from foreign matter consisting of, rocks, and the like. U.S. Pat. No. 3,612,274, issued Oct. 12, 1971, to Schmidt et al, states that while produce graders similar to Sherwood are effective when the color change between immature and overmature foods are great, sorting techniques which rely primarily on color are generally inadequate whenever the fdod which is desired to be sorted exhibits only a very small color change between immature and overmature and when the grades which are to be distinguished from each other display little if any color difference. This prior patent states that one food which exhibits only a small color change is corn. The food-sorting technique of the Schmidt patent sorts foods by sensing only a single light beam which is reflected from the food and measures characteristics such as color, size and texture of the food by use of only a single photoelectric cell. The patent states that the use of a single light source is an improvement over prior sorting methods in which additional photoelectric sorting methods and devices have been employed to grade foods either separately or in conjunction with color sorting. The Schmidt et al patent, however, senses the reflected light from the corn as the corn passes under the sensing device in a cross-wise manner, and thus the light strikes only a narrow band of the ear of corn.
The sorting and inspection system of the present invention not only automatically grades the maturity of the corn, but the system also automatically grades many other characteristics of the corn which cannot be accomplished utilizing the food sorting method and apparatus of the prior art patents. In the present invention, the whole ear of the corn is inspected automatically for color variations, size and numerous other characteristics by means of a plurality of photoelectric devices which heretofore have not been combined in a manner to provide substantially total automatic inspection and sorting of corn. The present invention has substantially eliminated the need for manually visualizing the corn for sorting acceptable produce from unacceptable produce. U.S. Pat. No. 2,791,330, issued May 7, 1957, to Carlson, discloses a machine for handling green corn including washing, visual inspection and culling, separation according to size, and delivery to cutting machines. The device is a mechanical device and does not utilize the photoelectric sensing means of the inspection and sorting system of the present invention. The Carlson patent still relies on significant visual inspection for sorting acceptable and unacceptable ears of corn.
Other patented inspection devices utilizing photoelectric sensing means include U.S. Pat. No. 3,038,606, issued June 12, 1962, to Leaver et al, which is utilized for inspecting the level of contents of cans or packages; U.S. Pat. No. 3,052,353, issued Sept. 4, 1962, to Pritchett, which discloses a means for sorting ore having a radioactive component; and U.S. Pat. No. 3,207,307, issued Sept. 21, 1965, to Means, which discloses a bobbin sorting mechanism.